The five most popular stories on CNN.com in the past 24 hours, according to NewsPulse.

Devastating earthquake, tsunami hit Japan: As the ground continued to twitch with aftershocks the morning after Japan was struck by the most powerful earthquake in the nation's ¬†recorded history, the disaster's massive impact was only beginning to be revealed.

U.S. man killed trying to photograph tsunami: California Gov. Jerry Brown declared a state of emergency Friday in four coastal counties, saying the ocean surge from tsunami waves spawned by an earthquake near Japan is imperiling infrastructure and public safety.

Japanese plants struggling, official says: Reactors at two Japanese power plants can no longer cool radioactive substances, a government official said Saturday, adding that a small leak had been detected at one of the facilities.

Japan, world watches tsunami strike live: Within an hour after a major earthquake rattled Japan, the nation and the world watched a surreal and unprecedented scene from a helicopter hovering above the

Tsunami warning issued for at least 50 areas: Tsunami waves that raced across the Pacific Ocean triggered warnings in more than 50 countries and territories Friday, but there were few immediate reports of major damage outside Japan.

An 8.9-magnitude earthquake hit northern Japan today, triggering tsunamis that sent a wave filled with boats and houses toward land. Hawaii and the U.S. West Coast are under a tsunami warning. Are you in an affected area? Send an iReport. Read the full report on how the quake hit Japan and generated a Pacific-wide tsunami.

[11:01 p.m. ET, 1:01 p.m. Tokyo] At least 398 people are dead and 805 are missing after the massive earthquake in Japan, the Kyodo News Agency reported Saturday. Earlier, the news agency said the death toll from the massive earthquake would likely surpass 1,000.

[10:01 p.m. ET, 12:01 p.m. Tokyo] As rescue crews continue to account for the damage caused by the country's largest earthquake on record, people in Japan on Saturday are struggling to contact loved ones near the hardest hit areas.

Lucy Craft, a freelance correspondent in Tokyo, has a teenage son at a high school near the epicenter in Sendai, northeast of Tokyo. More than 18 hours after the quake, she hadn't been able to make contact.

"The phone lines are still down... I haven't been able to get in touch with him by cell phone, I haven't been able to contact anybody there. I have his teacher's phone number," Craft said Saturday morning in Tokyo. "It's a very upsetting situation, as you can imagine."

Roads and buildings showed cracks as far away as 200 kilometers (125 miles) from Sendai, the closest city to the epicenter. One man told CNN the scene in towns hit by the quake and the resulting tsunami was "unimaginable."

Shoppers were polite but tense as they sought food, water and gasoline from stores where shelves were quickly emptied and pumps soon ran dry.

[9:20 p.m. ET, 11:20 a.m. Tokyo] ÔĽŅAt least 200 people are dead in Japan, 700 are missing, and the death toll is increasing every hour since a devastating earthquake hit the country Friday, Japan's ambassador to the United States said.

"This is the most terribible earthquake we've had," Ichiro Fujisaki told CNN's Piers Morgan. "This is a terrible incident that has hit Japan."

At least six million homes are without electricity, accounting for about 10 percent of Japan's households, he said. The government is responding to recovery efforts with 8,000 self-defense forces, and the Coast Guard is contributing 300 ships and 40 airplanes, he said.

"We are mobilizing all we can."

[8:30 p.m. ET, 10:30 a.m. Tokyo] ÔĽŅEcuadorian President Rafael Correa ordered the evacuation of the Galapagos Islands and of cities along the country's coast Friday.

Millions of people have been affected after a devastating earthquake hit Japan on Friday. An estimated hundreds have been killed, and many more are¬†planning for aftershocks. Here are some personal stories from around the world:

- iReporter Christopher Lacey was standing on his back deck, talking on the phone about the events in Japan when he noticed a disturbance in the waters of Richardson Bay, which is part of the San Francisco Bay.

"The waves did not appear to be more than about 3 feet high from my perspective."

- iReporter Kristi Marie Gott narrates what happened when she heard the tsunami warning, in Florence, Oregon early this morning. "I wanted to let people see what the tsunami surges looked like on the Oregon Coast near Heceta Head Lighthouse. To a local person it was amazing to see the ocean surge back as the water withdrew, leaving the shallows and rocks visible, then surge forward again covering them all the way to the cliffs. I go there all the time so it was clear this was very different from the usual waves or tides."

- iReporter Travis Richardson, of Fremont, California, was evacuated from his hotel in Tokyo and recorded some images of a massive fire nearby.

"We were forced to leave the hotel and stand outside, I could see the big billowing dark smoke coming from I'm guessing an oil rig possible approximately 4 to 5 miles away and pulled out my iPhone to take photos and video. Thought I should document this, everyone was standing outside. When the aftershocks happened they told us to move further away from the hotel and stand in the grassy area between the buildings."

CNN Senior International Correspondent Nic Robertson and his crew were detained Friday in Tajura, Libya, east of Tripoli by forces loyal to Libyan leader Moammar Gadhafi. This is his account.

For a few moments today, for us personally, Libya‚Äôs lies and deceit were swept aside and the real deal was brutally exposed.

‚ÄúItla, itla‚ÄĚ - "Get in the car, get in the car!" - he was screaming. My cameraman, Khalil Abdallah, and I hesitated for a split-second. But that's all it was.

We were staring down the barrel of an AK-47, the weapon was jumping in his hands. He was cocking it, wrenching the handle back, a bullet being slammed into the firing chamber.

It was only a split-second.

We are free to go anywhere, any time, talk to who we want, when we want. That's what Moammar Gadhafi‚Äôs son told me, that's what Libya told the U.N. We already knew it was all lies - look at any number of our colleagues, arrested, detained, in some cases, beaten - but today it came home to us personally.

The hyper-aggressive jerk with the gun had just hit the jackpot.

There was him and three others. They were grabbing us, bundling us towards their pickup truck. He had a pistol in his belt, one of the others kept his AK trained on us too, and an older guy with the grey beard was speed-dialing his phone.

Editor's note: Nancy Grace's new show on HLN, "Nancy Grace: America's Missing," is dedicated to finding 50 people in 50 days. As part of the effort, which relies heavily on audience participation, CNN.com's news blog This Just In will feature the stories of the missing.

This is the 40th case.

Tangena Hussein was 2 when her mother's boyfriend reported her missing in Detroit on October 2, 2008.

The man told police he put her in his car, and he began driving to a mall to pick up Tangena's mother from work. On the way, he stopped at a Detroit gas station, left Tangena in his locked car and went inside the store to get some gum, he told police.

He told police that when he exited the gas station, Tangena was no longer in the car. He reportedly drove to the mall to pick up Tangena's mother before returning to the gas station to call police and report the girl's disappearance.

Police say the vehicle showed no signs of forced entry. They say they don't know what happened to Tangena.

Oklahoma Governor Mary Fallin today declared a State of Emergency for all 77 Oklahoma counties as more than two dozen wildfires spread across the state, causing evacuations.

"Our thoughts and prayers are with all Oklahomans who have been impacted by these fires as well as our emergency responders in harms' way," Fallin said. "We know homes, as well as other property, have been lost and we will work to do everything we can to help Oklahomans during their time of need."

Under the Executive Order, state agencies can make emergency purchases and acquisitions needed to expedite the delivery of resources to local jurisdictions. The declaration also marks a first step toward seeking federal assistance should it be necessary.

Actor Mel Gibson entered a "no contest" plea Friday afternoon to a misdemeanor battery charge relating to an incident a year ago involving his former girlfriend.

Los Angeles County Judge Stephanie Sautner accepted a plea deal that puts the actor on unsupervised probation for three years and requires Gibson to complete 52 weeks of anger management counseling.

"No contest, pursuant to People v. West," Gibson said, when Judge Sautner asked for his plea.

The "West plea" allows a defendant to enter a no contest plea without admitting guilt.

Los Angeles County Deputy District Attorney Simone Shay told the court the prosecution accepted the plea deal "to lessen the trauma and impact of any court proceedings on the victim and minor witness."

Talks aimed at averting a work stoppage in the National Football League broke down Friday, with the players' union declaring it is decertifying itself in a move expected to launch a lengthy legal battle with owners.

"The NFL Players Association announced today it has informed the NFL, NFL clubs and other necessary parties that it has renounced its status as the exclusive collective bargaining representative of the players of the National Football League," the association said in a statement.

"The NFLPA will move forward as a professional trade association with the mission of supporting the interests and rights of current and former professional football players."

The military forces of Moammar Gadhafi on Friday pounded Ras Lanuf, the key oil port once in the hands of rebel forces, with its leadership confidently vowing to retake all territory from the opposition despite growing international pressure.

Even as it targeted its domestic enemies, the Tripoli government continued to parry with leaders around the globe.

Deputy Foreign Minister Khaled Kaim, for instance, said Friday that Libya has suspended diplomatic relations with France, one day after the French government recognized the newly created Libyan opposition movement as the sole representative of the country.

In Ras Lanuf, pro-Gadhafi forces cranked up an intense and steady bombardment of the city, believed to be by rocket, artillery and tank fire. A storage tank at an oil refinery was on fire after an air raid there.

"We saw a bomb fall about a kilometer to the southwest of the refinery, and moments later saw thick black smoke rising from the refinery. We don't know, and no one we spoke to could say with any level of certainty or veracity, what caused the fire," said CNN Correspondent Ben Wedeman.

What does it sound like in the middle of a powerful and deadly earthquake?

Through his work with the American Society of Civil Engineers, Ron Hamburger has lived through dozens of quake aftermaths and aftershocks while studying their damage on buildings and other infrastructure.

As most people know, the intense shaking of the ground inflicts incredible stresses on buildings. But what may not be so apparent is how these noises offer clues to what's really happening inside the floors and walls of each structure.

Buildings made of steel or reinforced concrete don't topple from earthquakes very often. But when they do, they make very loud and scary noises, Hamburger says.

The power of water can be so destructive it can kill thousands of people in seconds with little warning.

The U.S. is lucky that it knew about a threat of a tsunami and had hours to prepare and evacuate following Friday's massive earthquake in Japan.

Japan was inundated with as much as 30 feet of water shortly after the 8.9-magnitude quake. Residents had about a 15-minute warning to get to higher ground. The death toll is already in the hundreds and still rising.¬†Tsunami warnings were issued for the entire Pacific basin.

When a powerful earthquake moves the seafloor and displaces water, it spawns a tsunami, a series of waves that can travel through the water for thousands of miles at speeds up to 600 mph.

"The listing of a tsunami time does not mean that a wave is imminent,"¬†NOAA said on its website. "The listed arrival time is the intitial wave arrival. Tsunamis can be dangerous for many hours after arrival, and the initial wave is not necessarily the largest."

A powerful earthquake in Japan has unleashed a tsunami threat across the Pacific region, including Hawaii and the Western United States.¬† Watch CNN.com Live for continuing coverage on this breaking story.

Today's programming highlights...

Ongoing coverage - Japan earthquake/Pacific tsunami threat

11:00 am ET¬†- Rep. Giffords health update - Doctors will update the public on the condition of Rep. Gabrielle Giffords, who is recovering from a gunshot wound to the head.

With the streets filled with pedestrians and motorists, the fire department is having a difficult time arriving to contain the fire, Postnikoff said.

"Many people back in (North) America who have not experienced a severe earthquake might scoff," Postnikoff said, "but the fact that the Earth shook strongly enough to form a CRACK shows what kind of power (and pressure) Japan is sitting overtop of."

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